N = int(input())
M = 2 * N - 1
L = [i for i in range(1,M+1)]
print(M)
K = [i for i in range(M,M-N,-1)]
cnt = 0
for c in range(M):
    print(*K)
    if c == M - 1:
        break
    for i in range(N):
        L[K[i]-1] -= 1
    P = list(K)
    for i in range(N):
        while L[P[i]-1] == 0:
            P[i] -= 1
        if i < N - 1 and P[i+1] == P[i]:
            P[i+1] = P[i] - 1
    if K == P:
        cnt += 1
        if cnt == 2:
            P[-1] -= 1
            while L[P[-1]-1] == 0:
                P[-1] -= 1
            cnt = 0
    else:
        cnt = 0
    K = list(P)